Popular Science Monthly/Volume 44/December 1893/Modern War Vessels of the United States
|MODERN WAR VESSELS OF THE UNITED STATES NAVY.|
to purposes of protection, a style of construction now universally adopted and known as cellular was developed by Sir E. J. Reed, then chief constructor of the British Navy, in which the maximum of strength with the minimum of weight was sought after and very fairly obtained. Then began, what has continued to this day, the race between armor and armament; the makers of armor striving to make plates that would effectually resist the largest guns, and the gun-makers using every means at their command to produce guns capable of breaking up or penetrating the heaviest armor. The outcome is, on the side of armor, the solid steel plate with a face case-hardened by the Fig. 2.—Iowa. Section through Armor. Harvey process—a face so hard that no drill will in the slightest degree affect it, and this extreme hardness gradually shaded off to a soft back to prevent through cracks. On the other hand is the steel built-up breech-loading gun, with a length of from thirty-five to forty-five times its diameter of bore, using slow-burning powder, having low initial pressures and giving a muzzle velocity from two thousand to twenty-five hundred feet per second, and special steel armor-piercing projectiles for the purpose of racking or breaking up the armor and then piercing the hulk This competition has indirectly opened up a new material of some twenty per centum greater strength when compared with wrought iron, known as mild steel, which naval architects are employing to enable them to produce lighter structures, and to use the weight saved in giving greater thickness to the armor, increased armament, or added power and speed, as the necessities of the design contemplated may demand. Shortly after the introduction of this material, or in 1882, the Congress of the United States appropriated for the construction of three cruisers and one dispatch boat, which are now familiar to us all under the names of the Chicago, Boston, Atlanta, and Dolphin; fortunately for our Government, its corps of naval constructors and engineers had by repeated visits to the ship-yards and gun factories abroad, and a close study of the principles involved in the new methods of construction, kept themselves fully abreast of the progress being made in shipbuilding, marine engineering, and naval artillery, and were thus enabled when the opportunity was given by Congress to promptly take up the work of rehabilitating the navy, and carry it forward successfully. Congress in its appropriation had stipulated that the new vessels were to be constructed of steel; this meant a considerable Fig. 3.—Iowa. Midship Section.
C, C, C, coal; P, P, P, passages. outlay in capital to the metal producers of the country, who, with the exception of some firms making a specialty of tool steel, had been engaged mainly in the manufacture of wrought iron. However, having full confidence in the determination of Congress to give the country a new navy, they did not hesitate to at once install plants capable of manufacturing steel suitable for shipbuilding and boiler construction, of steel of a higher grade for the construction of high-powered built-up guns, and of producing steel for armor plates weighing from thirty to forty tons each. It is worthy of note that these industries, built up within a decade under the stimulus given by the rebuilding of the navy, to-day challenge the world to produce better material. So rapid has been the progress of our manufacturers, and so fully have all demands upon them been met, that one of our shipbuilding firms is now constructing two mammoth steamers for the Inman International Line, whose vessels have, since its organization, been constructed on the other side of the Atlantic.
The types of war vessels considered by naval authorities to be best suited to the needs of our service may be classed in general terms as battle-ships, armored cruisers, protected cruisers, harbor-defense monitors, gunboats, torpedo-boats (surface and submarine), and rams. The uses and functions of each type differ greatly; some of the more prominent may be broadly stated here.
Taking first the battle-ships, we find them to be, of all the types of war vessels, the most powerful in the feature of offense and defense; they are intended to stand and fight, to give and take blows like giants in a prize ring; and the reason can be plainly seen when Fig. 4.—Iowa.
Section through Coffer Dams, etc. we appreciate the fact that an enemy can bring his battle-ship within twelve miles of our large seaboard cities, and there taking up a position of vantage, secure from any attack by land, shell the city; the only vessel, then, that can dispute possession with him point by point is a ship of similar powers of doing battle, however successful an attack by torpedo-boat, either surface or submarine, may be when the conditions are suitable. The points, therefore, to be emphasized in the design are protection and armament, or the power to deliver heavy blows with the ability to withstand those of its antagonist; with these must be combined power to enable it to act on the offensive, such as speed, endurance, habitability, and form of hull that will insure seaworthiness.
armament; their function in war is to capture the commerce-destroyers of the enemy, to act as commerce-destroyers themselves, and to convoy and protect fleets of large and fast merchant vessels. To accomplish these purposes great speed is necessary, either to overtake or convoy swift merchantmen; great endurance or coal supply, to enable them to keep the sea for long periods on the Fig. 6.—Brooklyn. Midship Section.
A, air duct; CE, cellulose; C, C, C, coal; P, P, P, passages. path usually frequented by merchant vessels; and offensive and defensive power sufficient to enable them to successfully resist the attacks of vessels of their own class.
The type next in importance and general usefulness is styled the protected cruiser, or those whose only protection against injury consists of sloping armor decks of varying thickness, in combination with coffer dams filled with water-excluding material and closely divided compartments in the region of the line of flotation. The characteristics of this type are not capable of being so clearly defined as those already considered, as they include such widely differing vessels as the triple-screw Columbia of 7,350 tons displacement, the Olympia of 5,500 tons, down to cruisers of 2,000 and 3,000 tons displacement as represented by the Cincinnati and Detroit. Their function is a varied though exceedingly useful one; some are designed particularly for preying upon the commerce of an enemy so as to cripple its resources, the most notable examples being the Columbia of our own and the Blake of the British Navy.Speed and endurance are the features emphasized, combined with guns of light caliber for dealing with unarmed vessels;
others again, like the Chicago, Newark, Baltimore, and San Francisco, are designed for purposes of general utility, such as protecting our mercantile interests abroad, the one feature emphasized being endurance, with those of speed, protection, and armament very fairly developed. Our gunboats of the Yorktown and Machias types are miniature cruisers, except that speed has been sacrificed to enable them to carry heavy batteries; at present they are constructed entirely of steel, although many fruitless efforts have been made to adopt in this class the style of construction known as composite that is, all the parts of steel as is customary, except the outer covering of the hull, which is formed of wood planking coppered instead of steel plating. This system has been most earnestly and ably advocated by Chief Naval Constructor Philip Hichborn, and has formed the subject of special reports by him to the Navy Department, but the wording of the congressional appropriations has been such as to preclude its adoption.
The advantages to be gained are cheapness and ease of maintenance, freedom from fouling and consequent ease of propulsion, with the ability to keep the sea for long periods without being docked. All vessels of war are in a certain sense compromises between speed, endurance, protection, and armament; no one feature can be largely developed without corresponding sacrifices in the development of the others: for example, if great speed is required, it entails machinery of great power and weight with a large supply of coal; the weights, therefore, of the other main features must necessarily be reduced in order to emphasize that of speed; therefore, when Congress has appropriated for a certain type of vessel and fixed the limit of cost, a very careful study of all existing vessels of the desired type is made by the designing staff of the construction department, the particular requirements of the service are considered, the features to be emphasized determined, and the results embodied in a carefully prepared design. It is a very usual custom, and perhaps a natural one, for the press, when the design is made public, to compare it with some similar vessel of a foreign navy whose conditions of service are very dissimilar, sometimes to the seeming disadvantage of the proposed vessel, especially when such criticism may have been suggested by private builders who desire greater latitude in certain directions, and the general public may receive the impression that the best has not been attained; but to those who know the care and study given to the preparation of the design in view of the service required, and are able to comprehend fully its military value, the conclusion is very different. Taking, then, our battle-ships, we find the highest representative in the Iowa (Fig. 1), now building at the Messrs. Cramp's, which has a displacement of 11,250 tons, and carries a battery of four 12-inch, eight 8-inch, and ten 4-inch breech-loading guns, besides twenty machine guns and six tubes for discharging 18-inch automobile torpedoes. It is one thing for a vessel to carry a large battery capable of firing a tremendous weight of metal when all the manipulating apparatus is in perfect order, but quite another in these days of high explosives to have that battery and apparatus securely protected from the guns of its antagonist, therefore the 13-inch forty-four-ton guns of the Iowa are mounted in pairs in turrets having walls of solid steel fifteen inches thick, and protected from the water-line up by steel of the same thickness, which effectually protects the loading, turning, and controlling mechanisms. In order that these guns may be fought in heavy weather the forward turret is placed on a forecastle deck with the axis of the guns some twenty-five feet above the load line, and has a train of three hundred degrees, or only sixty less than a complete circle; the after 12-inch guns are mounted in the same manner, but on a deck seven feet nearer the load line. Both forward and after turrets are placed in the mid line of the vessel, in order to have a great train and be as free as possible from the motion due to rolling; the turrets are revolved by steam power at the rate of one revolution per minute. Some idea of the power of these guns may be obtained from the following data: The weight of one powder charge is four hundred and twenty-five pounds; that of the projectile, eight hundred and fifty pounds; its muzzle velocity, 2,100 feet, or four tenths of a mile per second; the muzzle energy, 25,085 foot tons, or capable of raising that amount one foot in a minute, with a penetration in wrought iron of 27·6 inches. The 8-inch guns are also mounted in turrets, having great range, and are protected by armor varying from ten inches to seven inches and a half in thickness; the ten 4-inch guns, each discharging projectiles of thirty-six pounds weight at the rate of ten rounds per minute, are protected by fixed segmental shields four inches thick.While so much has been done to develop the battery and its protection, the features of defense, stability, speed, and endurance have received most careful attention; the magazines, boilers, engines, steering mechanism, etc., are all inclosed in a belt of steel, covering about sixty-five per cent of the load-line area, of a maximum thickness of fourteen inches, and extending from three feet above to five feet below the load line: at the upper edge of this is worked from side to side of the vessel a horizontal deck three inches thick (see Figs. 2 and 3); above this, to protect the stability, a steel belt four inches in thickness is worked to the main deck, and at the unarmored ends double coffer dams six feet wide, the outer one filled with obturating and the inner one with water-excluding material, are provided as shown in Fig. 4.
Great care has been given the water-tight subdivision, both above and below the armor belt, in order to prevent a catastrophe such as that which befell the Victoria; especially above the armor belt, where the subdivision of that unfortunate vessel was very weak, has the Iowa received most careful attention. The machinery is capable of developing 11,000 horse power, and will propel the vessel at a speed of seventeen knots per hour; the engines are of the triple-expansion type, being inverted, direct acting, and surface-condensing, driving twin screws. The coal supply is sufficient when steaming at ten knots to admit of crossing the Atlantic and back without recoaling. The United States steamship New York (Fig. 5), which lately created so much enthusiasm on account of her remarkable development of speed, is of the armored-cruiser type; but the Brooklyn, now being built under contract, is a very distinct advance upon the general design of the New York, and will here be taken as the exponent of her type. We find her to be provided with sufficient power to drive her at the rate of twenty-one knots or twenty-four miles per hour, and to have a coal supply of 1,800 tons, which will give her a very large radius of action. The main battery carried is eight 8-inch and twelve 5-inch breech-loading rifles; the 8-inch guns are mounted in pairs in turrets, protected by steel armor seven and a half and five inches in thickness; the 5-inch guns and the battery of machine guns, eighteen in number, are protected by steel armor varying in thickness from four to two inches. The protection to the hull, machinery, and magazines is afforded by a steel deck of a maximum thickness of six inches, being five feet below the load line at its outboard edges, and sloping upward and inward to the height of the load line on the flat portions, as shown in Fig. G.Beneath this deck are placed engines, boilers, magazines, steering gear, and electrical generating plant, in fact all such parts as would be injured by and disable the vessel if exposed to the enemy's fire. To protect the stability an armored belt four inches in thickness is worked from the sloping armor to four feet above the load line for the space occupied by the engines and boilers, the object being to provide resistance sufficient to cause high-explosive shells to explode before entering the sides of the vessel. Inside of this and extending the whole length of the vessel is a coffer dam of obturating material, as shown in the outline midship section. Fig. 6, and the spaces both above and below the armor deck are closely subdivided by longitudinal and athwartship bulkheads into many compartments in which coal and stores are stowed, thus as far as possible, with the means now at the command of the naval architect, precluding the sinking of the vessel when injured.
A class of vessels of much interest, on account of their great destructive capabilities when the conditions are suitable, is the torpedo vessel, of which the Ericsson (Fig. 7), now building, is a representative; they are lightly constructed and provided with powerful machinery to enable them to attain great speed, reaching as high as twenty-eight to thirty-five miles per hour. They are armed principally with torpedo-launching tubes from which are ejected, by compressed air, automobile torpedoes, capable of traveling at a rate of speed of twenty knots per hour at a predetermined depth. The boat or launching tube is trained directly upon the target, and the torpedoes are expelled in a direct line toward it, certain automatic rudders being acted upon by hydrostatic pressure to enable them to keep their course. The head is fitted with a torpedo net-cutting device to enable the torpedo to pass through the net protecting the ship's side and to explode against the side by impact. The most noteworthy achievement by this class of vessels was the blowing up and sinking of the Blanco Encalada by the Almirante Lynch during the late Chilian struggle.
In closing this article it seems eminently proper to acknowledge the distinguished services and untiring zeal of ex-Chief Constructor Theodore D. Wilson, who for eleven years, or during the period of rehabilitation, has most ably shaped the general design and construction of the hulls of our war vessels.